Externally-orientated internally-corrected perforating gun system and method

Abstract

An externally-oriented internally-corrected perforating gun system and method for accurate perforation in a deviated wellbore is disclosed. The system/method includes a gun string assembly (GSA) deployed in a wellbore with an external protuberance member (EPM) and an internal pivot support (IPS). With the EPM oriented to the high side of the wellbore, the center of mass of the GSA positions the GSA at the lower side of the wellbore surface. The IPS is attached to internal gun components such end plate, charge holder tube, detonating cord or charge case. The charges inside the charge holder tube move with the gravitational vector about the IPS and point more accurately in the desired direction for perforating. The external orientation of the EPM along with limited internal swing about the IPS provide for an accurate orientation of the charges that results in efficient and effective perforating through a hydrocarbon formation.

What is claimed is: 
     
       1. An externally-oriented internally-corrected perforating gun system for use in a wellbore casing comprising:
 (a) external protuberance member (EPM); and 
 (b) internal pivot support (IPS); 
 wherein 
 said perforating gun system comprises a plurality of perforating guns; 
 said external protuberance member is configured to be mounted on said perforating gun system; 
 said external protuberance member is configured to externally align said perforating gun system in a desired perforating orientation within a coarse angular range; and 
 said internal pivot support is configured to swivel plural energetic charges in said perforating gun system within a limited arc such that said plural energetic charges are aligned within a finer angular range in said desired perforating orientation. 
 
     
     
       2. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said internal pivot support is a pivot pin integrated to an end plate; said end plate is attached to a charge holder tube in said perforating gun; and said pivot pin limits rotation of said charge holder tube within said limited arc. 
     
     
       3. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said internal pivot support is a pin integrated to an end plate; said end plate is configured with a bearing race attached to a charge holder tube in said perforating guns; and said pin limits rotation of said charge holder tube within said limited arc. 
     
     
       4. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said internal pivot support is mechanically attached to a charge holder tube in said perforating gun. 
     
     
       5. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said internal pivot support is mechanically attached to a detonating cord; said detonating cord is fastened to a charge holder tube in said perforating gun. 
     
     
       6. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said internal pivot support is mechanically attached to a charge clip; said charge clip is configured to mechanically attach a charge case to a detonating cord; said charge case is configured to house said plural energetic devices. 
     
     
       7. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said internal pivot support is mechanically attached to a charge case; said charge case is configured to house said plural energetic charges. 
     
     
       8. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said EPM comprises a plurality of EPM's that are configured to be mounted at a plurality of coupling element locations of said perforating gun system. 
     
     
       9. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said EPM is configured to be mounted on at least one of said plurality of perforating guns. 
     
     
       10. The externally-oriented internally-corrected perforating gun of  claim 1  wherein said IPS is configured with eccentric weights to internally orient said charges in said desired perforating orientation. 
     
     
       11. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said finer angular range is within +/−5 degrees. 
     
     
       12. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said coarser angular range is within +/−20 degrees. 
     
     
       13. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said EPM shape is an elongated shape. 
     
     
       14. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said EPM comprises a plurality of EPMs that are angularly offset to each other. 
     
     
       15. The externally-oriented internally-corrected perforating gun system of  claim 1  wherein said EPM comprises a plurality of EPMs that are randomly spaced. 
     
     
       16. The externally-oriented internally-corrected perforating gun system of  claim 1  further comprises a secondary internal pivot support; said secondary internal pivot support is attached to a detonating cord in said perforating gun; said secondary internal pivot support is configured to swivel said plural charges along a longitudinal axis of said perforating gun to orient said charges within a precise angular range. 
     
     
       17. The externally-oriented internally-corrected perforating gun system of  claim 1  further comprises a secondary internal pivot support; said secondary internal pivot support is attached to a detonating cord in said perforating gun; said secondary internal pivot support is configured to swivel said plural charges orthogonally to the length of said perforating gun to orient said charges within a precise angular range. 
     
     
       18. The externally-oriented internally-corrected perforating gun system of  claim 16  wherein said precise angular range is within +/−5 degrees. 
     
     
       19. The externally-oriented internally-corrected perforating gun system of  claim 17  wherein said precise angular range is within +/−5 degrees. 
     
     
       20. The externally-oriented internally-corrected perforating gun system of  claim 1  further comprises an external orienting weight; said external orienting weight is configured to be attached to an end of said perforating gun system. 
     
     
       21. An externally-oriented internally-corrected perforating gun method, said method operating in conjunction with an externally-oriented internally-corrected perforating gun system, said system comprising:
 (a) external protuberance member (EPM); and 
 (b) internal pivot support (IPS); 
 wherein 
 said perforating gun system comprises a plurality of perforating guns; 
 said external protuberance member is configured to be mounted on said perforating gun system; 
 said external protuberance member is configured to externally align said perforating gun system in a desired perforating orientation within a coarse angular range; and 
 said internal pivot support is configured to swivel plural energetic charges in said perforating gun system within a limited arc such that said plural energetic charges are aligned within a finer angular range in said desired perforating orientation; 
 wherein said method comprises the steps of: 
 (1) positioning said perforating gun system in a wellbore casing; 
 (2) orienting coarsely with said EPM in said desired perforating orientation within said coarse angular range; 
 (3) correcting finely with said IPS in said desired perforating orientation within said fine angular range; and 
 (4) perforating with said perforating gun system into a hydrocarbon formation.